Room thermostat



y 1939- w. H. HUTCHINS 2,160,740

ROOM THERMOSTAT Filed April 10, 1936 Patented May 30, 1939 2,160,740

UNITED STATES PATENT OFFICE ROOM THERMOSTAT William H. Hutchins, Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application April 10, 1936, Serial No. 73,621

1 Claim. (Cl. 200-138) This invention relates generally to thermostatic element taken substantially on line 4-4 static electric switches and more particularly to of Fig. 2. that type of switch which is termed a room ther- As this invention relates primarily to the addimostat and employed in electric circuits such as tion or association of an air circulating fan with 5 for operating dampers in domestic heating systhe thermostatic element of the room thermostat 5 tems and for controlling the operation of door other type of thermostatic electric switch, it mestic fluid fuel burners. will be understood that the thermostatic element When used in domestic heating systems of any and switch and switch operating mechanism may character, the thermostat is located in the room be of any conventional or standard construction.

of the dwelling in which it is most desirable to There has, therefore, been shown rather dia- 10 maintain a practically uniform temperature. grammatically a room thermostat of conven- The operation of the thermostat is controlled by tional internal construction in which the thersome means responsive to temperature changes, mostatic element takes the form of a bi-metallic such as a coil of thermostatic metal or a bicoil I. The inner end of this coil is secured to metallic coil, or a bellows or the like containing an arm 2 on the adiusting member 3 mounted 15 a fluid which expands or contracts in response on shaft 4. This adjusting member 3 extends to changes of temperature of the surrounding upwardly and has an outward extension 5 atmosphere, and is adapted to openor close an through the front face of the thermostat caselectric switch at a certain temperature in the ing 6 to constitute a handle for adjusting the angular position of the thermostatic element on 20 To maintain practically uniform temperature, the shaft 4 in the usual manner. it is highly desirable that the thermostat will The outer end of the bi-metallic coil I extends respond quickly to any changes in the temperaupwardly and carries a permanent magnet which ture of the surrounding atmosphere, and in conis adapted to be moved toward and away from ventional thermostats it has been found that the the mercury tube 1 in response to temperature 25 mass of the unit as well as adjacent objects has changes affecting the coil. This magnet serves the effect of retarding the immediate response to close switch contacts in the mercury tube to room temperature changes. Also in many when moved toward or when it approaches to instances there is a stratification or poor circuwithin a predetermined distance from the tube,

lation of the air. in the immediate vicinity of and permit the contacts in the tube to open when 30 the thermostat so that it does not respond propmoved away from the tubeerly to changes in the average room temperature. The 6881118 18 provided on its fmht face with It is therefore the object of this invention to e calibrated scale which is with the Provide a thermostatic electric switch or room extension 5 of the adjusting member, and

I thermostat in which there is a positive circulamounts the usual thermmem The side walls J5 tion of air over the thermostatic element at all 0! the 035i!!! e ed with plurality of times to thereby maintain the temperature of ep nings II and the bottom of the casing 6 opens this element at the same temperature as that in 1101181118 the room in which the thermostat is placed, and The housing contains shah electric motor l2 which has a vertical shaft l3 carrying a fan 40 cause the thermostat to respond quickly to my or blower l4 at its upper end. A partition I! is 4 2: 2:32.3: 323 objects in iew the provided in the housing ll between the motor er v and fan and it will be noted that the space above vention consists in the provision of a small mothis partition m which the fan is located com m drive which is mated municates directly with the interior of the cas- 45 mostat in such a way as to circulate air over the ing 8 at the bottom thereon thermostatic element at all times. The front of the hm H is formed with a In the drawing: plurality of openings Ii above the partition Ii,

Fig. 1 is a view in front elevation with parts and the (an adapted to m uthrough broken away of one embodiment of the invention. the side Opening, in the casing and Marge P18- 2 is a ve i al cr Section taken suhlhmthe air through the openings II as shown by the tially online 2! of Fig. 1. arrows in Figs. 2 and 3.

Fig. 3 is a horizontal cross section taken sub- When the motor I! is operating it will therestantially on line 1-! of Fig. 1. fore be seen that the fan or blower will function Pig. 4 is a fragmentary view of the thermoto provide a continuous and positive circulation 5 of air over the thermostatic element. It is contemplated that the motor would be operated throughout the winter months when the room thermostat is in use and a manual switch provided in the motor circuit to shut off the motor, if desired, during the summer months.

Although the fan or blower has been disclosed as adapted to draw air downwardly over the thermostatic element, it will be understood that the fan or blower can be so arranged as to blow the air over the thermostatic element, and in fact, located with reference thereto in any desired manner that would serve to provide for a positive circulation of air.

It should also be understood that the motor and fan unit can be so constructed and arranged as to be readily associated with any conventional room thermostat or other type of thermostatic electric switch, and various other changes and modifications are possible without departing from the scope of the present invention.

I claim:

The combination in a room thermostat, of an electric switch and a thermostatic element for operating said switch, an electric motor, and a fan driven thereby, means substantially enclosing all of said elements and providing a plurality of chambers comprising a first chamber enclosing said switch and thermostatic element, a second chamber enclosing said fan, and a third chamber enclosing said motor, said first and second chambers communicating with each other and formed with air inlet and outlet openings whereby said fan will circulate air from outside of said means over said thermostatic element.

' WILLIAM H. HUTCHINS. 

